The present invention relates to radiographic apparatus and, more particularly, to apparatus for direct charge readout electron radiography apparatus having an improved electrode for increasing signal-to-noise ratio.
Radiography, particularly for medical diagnostic purposes, has been hampered by the need to record images on silver-based films, which are not only expensive but also require large storage volume therefor. One metod advanced for obtaining a radiograph without utilizing a film, causes a pattern of electrical charge to be deposited on the surface of a member, responsive to X-radiation differentially absorbed by an object to be analyzed. The two-dimensional surface of the member is scanned and the electronic charge at each scanned point is read out as an electrical signal capable of being processed by computer techniques. Known computer techniques can be applied to reconstruct, view and/or store the image. In particular, the reconstructed image can be developed by electrostatic and the like methods (eliminating the need for more-costly silver halide films) and can be modified in size to simplify the storage of the image. Known apparatus for accomplishing the conversion of X-radiation to electric charge, with subsequent readout of the charge, generally exhibit a signal-to-noise ratio which is not large enough for practical application of the apparatus with low radiation dosage.